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Fungal bio films

The kingdom of Fungi combines the unicellular microorganisms (yeasts) and multicellular organism known as mushrooms. The major difference of fungi and other living organisms (plants, bacteria, protists, and animals) is the presence of chitin in their cellular wall. Microscopic fungi usually are found in two distinct morphological forms, yeasts and molds (filamentous fungi).

A particular class of fungi known as dimorphic fungi can take the morphological characteristics of mold/filament/hypha or even yeast.

Even if not many fungi display dimorphism, the examples include Candida albicans and Penicillium marneffei.

As a concern to humans a lot of fungi are able to produce mycotoxins. These biological compounds present a toxic activity for animals or plants and can develop human diseases called mycotoxicosis. The consequences of this disease are influenced not only by age, health, and immune system of the patient but also by the concentration, type of mycotoxin, and length of exposure.

Surface of medical devices with different synthetic compositions (polymers, ceramics, glass, silicone, and metals) could be colonized by fungi.

The most recognized fungal infections are those related to Candida species. These infections lead to negative effects especially for the immune-compromised patients. The long-term administration of antifungal drugs is associated with systemic side- effects. The rate of mortality associated with Candida infections is over 45% in the whole world (Playford et al., 2008).

Among fungal species that cause invasive infection and develop biofilms, Aspergillus sp. (Beauvais and Muller, 2009), Cryptococcus sp. (Martinez and Casadevall, 2007), Trichosporon sp., Coccidioides sp., and Pneumocystis sp. are the most investigated. The most important factors involved in the formation of any biofilm are the source of nourishment, binding molecules, and the properties of contact surface. Biofilms formed by Candida species consist of yeast-form and hyphal cells and can develop on many biotic and abiotic surfaces. The growth process is represented by the attachment to a substrate, proliferation of yeast to the hyphal structures with the accumulation of extracellular matrix as the biofilm matures, and dispersal of cells from the mature biofilm to new niches.

Researches on the field of Aspergillus fumigatus revealed that this fungus is the second most common cause of invasive aspergillosis (Perfect and Cox, 2001).

The highest risk of biofilm-associated infections in the case of fungal pathogen belonging to Trichosporon genus is associated with Trichosporon asahii. The development of biofilms in this case includes yeast and hyphal cells within a polysaccharide matrix (Davis et al., 2002).

Although reported in several fungal infections, hyphal formation is not a uniform feature of fungal biofilms (Cushion et al., 2009).

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